Ten Random Openings

1. Necromancer's Portal. Leads to the nearest 1d6: 1 mausoleum; 2 mortuary; 3 top of the ancient burial mound; 4 funeral home; 5 torture chamber; 6 ossuary. If you don't know the magic password, the connection is one-way.
2. Kobold Mine Entrance. Leads to an ancient kobold mine, thirteen levels deep. Lots of rare and valuable ores and some magical crystals can be found there but the corridors are really, REALLY low and narrow. 
3. Non-Obviously Trapped Door. 1d6: 1 Level-Draining Handle; 2 Acid-Spitting Door Clapper; 3 Ridden with Devourer Maggots; 4 Door Mimic; 5 Paralyzing Handle; 6 Swarm-Summoning Alarm.
4. Demonic Well. If granted an offering such as gold or live sacrifice, can answer any question but does it in very insulting way. Water from the well is mildly poisonous, even for the creatures that are immune to non-magical poison. The Well leads to Hell itself.
5. Closet to Retardia. A door hidden in a closet that leads to a sizeable pocket dimension of a fairytale land. Sadly, all its inhabitants are as dumb as rocks, all coins,gems and jewelry are fake and all livestock and most of flowers are carnivorous and always hungry.
6. Window of Visions. A peculiar, large window, always showing dark, overcast sky. If one should stare into the clouds for at least 10 minutes, the Window will show a vision of the most important event that took place the day before and occurred less than 10 miles from the spectator. If someone enters the cloudy realm of the Window, becomes lost forever in the dreadful Dimension of Swirling Eyeballs.
7. Foul Cavern. Locals tell stories of the druidic treasure hidden in the cavern for centuries. Obviously, the cave is inhabited / guarded by a nasty beast. 1d6: 1 Three-Headed Bear; 2 Putrid Ram Demon; 3 Skeletal Duelists; 4 Troglodytic Werebats; 5 Tar Worm (largest in the province); 6 Swarm of Fist-Sized Lice.
8. Mysterious Stairway. They say it appeared overnight. Large, stone stairs lead to 1d6: 1 the Divine Cellar; 2 the Tunnels of Thousand Sounds; 3 sadly, nowhere; 4 the Prison of Headless Illusionist; 5 the Decaying Museum; 6 the Navidson's House.
9. Dimensional Fissure. One-way tear in the fabric of reality, leading to our world from 1d6: Realm of Slug Philosophers; 2 Sea of Primordial Souls; 3 Galactic Anthill; 4 Rodent Purgatory; 5 Land of Sulfuric Storms; 6 Bovine Heavens.
10. Magical Peephole. Allows to look into 1d12: 1 Goblin Ballroom; 2 Boudoir of the Queen of Retardia; 3 Needle Demon's Trap Cell; 4 Butter Wizard's Wardrobe; 6 Kaleidoscopic Museum; 7 Hypnotic Garden; 8 Trollish Latrine; 9 Secret War Room; 10 Lecture Hall in Elemental University; 11 Spy Ring Meeting Place; 12 Realm of the All-Seeing Eye.